public class Circle{
public double radius;
public Circle(double radius){this.radius=radius;}
public void showPerimeter(){
double perimeter = 2*Math.PI*radius;
System.out.printf("周长：%.2f\n",perimeter);
}
public void showArea(){
double area=Math.PI*radius*radius;
System.out.printf("面积：%.2f\n",area);
}
}
